2. speakers
  3. 188384-20253

Subwoofer speed is in the room, not the box

First, if you like swarm, that’s fine, please start a thread somewhere else about how much you like swarm.

I want to talk about the impression that subs are fast or slow compared to planar or line sources.

The concern, and it’s correct, is that adding a subwoofer to say a Martin Logan or Magneplanar speaker will ruin the sound balance. That concern is absolutely a valid one and can happen with almost any speaker, not just speakers with tight dispersion control.

What usually happens is that the room, sub and main speakers aren’t integrating very well. Unfortunately for most audiophiles, it’s very hard to figure out exactly what is wrong without measurements or EQ capabilities in the subwoofer to help you.

So, there’s the myth of a small sub being "faster." It isn’t. It’s slower has worst distortion and lower output than a larger sub but what it does is it doesn’t go down deep enough to wake the dragons.

The biggest problems I’ve heard/seen have been excessively large peaks in the subwoofer range. Sometimes those peaks put out 20x more power into a room than the rest of the subwoofer. Think about that!! Your 1000 W sub is putting out 20,000 watts worth of power in some very narrow bands. Of course that will sound bad and muddied. The combination of sub and main speaker can also excessively accentuate the area where they meet, not to mention nulls.

A lot is made about nulls in the bass but honestly IMHO, those are the least of our worries. Of course too many of them can make the bass drop out, but in practicality is is the irregular bass response and the massive peaks that most prevent any good sub from functioning well in a room.

Bass traps are of course very useful tools to help tame peaks and nulls. They can enable EQ in ways you can’t do without it. If your main speakers are ported, plug them. Us the AM Acoustics room mode simulator to help you place your speakers and listening location.

Lastly, using a subwoofer to only fill in 20 Hz range is nonsense. Go big or go home. Use a sub at least at 60 Hz or higher. Use a single cap to create a high pass filter. Use EQ on the subwoofer at least. Get bass traps. Measure, for heaven’s sake measure and stop imagining you know a thing about your speaker or subwoofer’s response in the room because you don’t. Once that speaker arrives in the room it’s a completely different animal than it was in the showroom or in the spec sheet.

Lastly, if your room is excessively reflective, you don’t need a sub, you need more absorption. By lowering the mid-hi energy levels in a room the bass will appear like an old Spanish galleon at low tide.

erik_squires
mijostyn's avatar
mijostyn
8,570 posts
 

@phusis I have no experience with horn subwoofer. For most of us they are impractical do to size constraints. For sure distortion will be lower for any given size driver due to efficiency. They problem is low bass will rattle and resonate almost anything. IMHO is is much easier to make a small enclosure resonance free with clever design and balanced force construction. It will not come remotely close to the efficiency of a horn but is way more practical from a size perspective. You are doing exactly as I suggested for crossover and slope. The game is keeping the sub out of the midrange or you will have mud. You are running 85 Hz @ 36 dB/oct. If you move up to 100 Hz you will have to steepen the slope. I can change crossover points and slopes on the fly which is very helpful for AB comparisons. 

@audioquest4life  The largest I would go is 15". The reason is the larger drivers have more trouble maintaining pistonic motion, they wobble. If you want more subwoofer use multiples of smaller drivers. Two 12's make a 15. Two 15s make an 18. So, go with four 15s. I use 12" drivers because the 15's would require a larger enclosure which will not fit in my situation and larger enclosures are more difficult to control from a resonance perspective.

@gdaddy1 Rel is only interested in selling as many subwoofers as they can. Their method of implementation is worse than silly. 

 

mijostyn's avatar
mijostyn
8,570 posts
 

@benanders The solution to your problem is digital bass management with room control, which is really speaker control. You can change the volume of the subs instantly with sliders for each individual channel on the computer. Room control will even out the frequency response of the sub with the best response at the listening position. I advance the volume of the subwoofers by 6 dB. with the crossover point and slope I use this gives live recordings the thump of the real experience at less than ear damaging levels and I do not change it at all for any given recording. These are choices that the mastering engineer makes and who am I to alter his art? 

Digital bas management uses measurements you make of your system. It sets the crossover point and slope, and aligns the subs with the mains in time and phase perfectly. After the system is set up it will be flat and your only adjustment by ear or feeling is relative volume. Low bass you feel more than hear. Go to a live jazz club and feel the bass and drums. That is what you want at home without being able to identify the subwoofers by ear. If you can hear the subs as individual drivers you need to rethink your integration. 

gdaddy1
135 posts
 

@mijostyn Rel is only interested in selling as many subwoofers as they can. Their method of implementation is worse than silly. 

Is it just REL you think is silly or are all sub manufacturers silly?

I just came back from the Tampa audio show and had this very discussion with SVS.  They said they don't suggest higher than 50hz. Cutting off main speakers that are perfectly capable of producing deep base is something they don't recommend. Their words, not mine. 

Silliness prevailed.... I couldn't find ONE room where anyone cut the main speakers with high crossed subs. Not one. Many of the displays had NO subs and the speakers alone were more than capable of producing deep powerful (dare I say fast?) bass. Their display only used subs for home theater demonstration. 2 channel stereo was speakers only.  

So the question is...If the high pass method makes the speaker sound so much better, wouldn't every speaker manufacturer use this superior method? Are all these displays competing for high end sound missing the secret sauce that would make their speakers sound even better?  Are they ALL silly?

 

 

benanders's avatar
benanders
234 posts
 
mijostyn

7,990 posts

@benanders The solution to your problem is digital bass management with room control, which is really speaker control. You can change the volume of the subs instantly with sliders for each individual channel on the computer.


@mijostyn I agree this would be the most typical solution. I even implemented a rather basic version that could be controlled with a smartphone app slider (and in real time IIRC). That was genuinely great for convenience, but required even higher dial setting on the plate amps than the passive preamp I tried. Literally no (digital) file I’ve played requires (level) dial setting past 3pm (most not beyond 1pm) for “glorious bass,” but certain newer recordings can easily shake the all-concrete room at same approx. gain (as measured for dB with subs off) due to bumps in some albums/versions bass frequencies…

 

I advance the volume of the subwoofers by 6 dB. with the crossover point and slope I use this gives live recordings the thump of the real experience at less than ear damaging levels and I do not change it at all for any given recording. These are choices that the mastering engineer makes and who am I to alter his art?

 

So I say I, I 😅 am the one to alter the art (italics in quote mine for emphasis). I think this may be the true discrepancy. I do not share a hands-off [the proportional frequencies] mindset, as the work of some masterings is just tailored for a bass environment I don’t recognize. I much rather not run plate amps near max to squeeze more convenient control over this (seems simply a psychological conflict of interests in my case - ease of control vs. concern over fatigue to sub amps); but again - I surely don’t argue this is the most conventional and hassle-free approach once subs are properly integrated.

This article helped my thinking on the matter; it was published about the same time I finally started realizing just how (file-/pressing-/master-) version-dependent music playback characteristics can be, before the mechanical / layout characteristics of the kit and room factor in. It’s also part of the reasoning I’m not bashful in thinking glorious bass doesn’t necessarily require taking whatever proportional level the (re?)masterer determined. Just my perception; subject to change without notice. 😉

 

 

clio09
3,356 posts
 

So the question is...If the high pass method makes the speaker sound so much better, wouldn't every speaker manufacturer use this superior method? Are all these displays competing for high end sound missing the secret sauce that would make their speakers sound even better?  Are they ALL silly?

If anything is silly its this statement. The better solution isn't always the one that the majority of manufacturers would choose to market or the one that consumers would choose to employ. It's been proven many times over with products across multiple industries. From a business perspective it's almost always about following the money.

I find it a bit strange no one to this point has brought up the amplifier in this conversation. If the amplifier could talk and express an opinion on filters, slopes, and frequencies, not to mention phase and damping we might be a bit surprised. After all its the amp that is coupled to the speaker.

Lastly, one of the reasons I actively bi-amp using separate amplification for the mains and the passive woofers is I still don't feel an amp, let alone a plate amp belongs in a box with the low frequency driver(s). I'm sure over the last several years the technology has improved but I still remain a bit stubborn here, as I once was about using subs altogether. Maybe I just need a bit more time.

More to discover